Get a Test. No Don't. Repeat.

By GINA KOLATA

Published: November 22, 2009

The current dispute over mammograms gives many people who've been around since the 1980s a sense of d? vu. Like archeologists arguing endlessly over the same set of bones, cancer specialists, it can seem, have been arguing endlessly over pretty much the same set of data.

The problem is that the screening test is not very helpful in preventing breast cancer deaths. Current estimates are that it reduces the death rate by 15 percent. If it were completely effective it would reduce the death rate by 100 percent. And screening has some downsides. It leads to false positives and unnecessary biopsies.

But more important, and only recently recognized, it leads to overdiagnosis -- the test is finding cancers that grow so slowly that if they were left alone they would never be noticed or cause any problem in a woman's lifetime. Since the harmless cancers look the same as deadly cancers, they are treated as if they are potentially lethal, with surgery, chemotherapy and radiation.

So the arguments continue to rage over risks and benefits, and over how strongly to recommend mammograms, and for whom, just as they have for decades:

1963 Health Insurance Plan of New York, or HIP, begins first mammography trial.

1977-83 Four randomized trials are begun in Europe; eventually, they find that mammography cuts the breast cancer death rate by up to 30 percent. But two in Canada find no benefit for women in their 40s, and find a breast examination equally effective for women over 50.

1979 A National Institutes of Health conference recommends annual screening for women 50 and older. It supports screening for women in their 40s only if they have had cancer or a family history of it.

1980s After sharp debate, the National Cancer Institute recommends routine screening for women in their 40s.

1989 Eleven health care organizations recommend an initial baseline mammogram for women age 35 to 39, and mammograms every one to two years for women over 40.

1992 The American Cancer Society drops its recommendation for baseline mammography for women 35 to 39.

1993 Citing growing evidence from randomized trials, the National Cancer Institute drops its recommendation for screening in the 40s.

1997 A National Institutes of Health conference concludes that there is not enough evidence to recommend routine screening for women in their 40s. But the Senate votes to encourage an institute advisory board to reject that conclusion, and the institute recommends beginning mammography in the 40s and continuing every one to two years.

1997 The American Cancer Society recommends annual mammography for all women over 40, and clinical breast exams close to or, preferably, just before the annual mammogram.

2001 A Danish study questions the findings of earlier trials and suggests that mammography's value may have been overstated.

2002 After reviewing the research, an independent panel at the National Cancer Institute decides it can no longer make a recommendation on whether women should be screened. The institute concludes that the new analysis did not refute evidence that mammography is effective, and stands by its earlier recommendation: women 40 and older should have routine screening.

2007 Guidelines issued by the American College of Physicians acknowledge that regular mammograms for women in their 40s can reduce the risk of dying from breast cancer by a modest amount. But a very high percentage will get false positive results that lead to unnecessary biopsies, increased costs and risks of injury. The college recommends that women in their 40s and their doctors periodically evaluate their risk to guide screening decisions.

2008 A Norwegian study in the Archives of Internal Medicine suggests that some invasive breast cancers may go away without treatment, raising the possibility that some cancers detected by mammograms may ''spontaneously regress.

November 2009 New guidelines published in The Annals of Internal Medicine recommend that most women start regular breast cancer screening at age 50, not 40, and that women age 50 to 74 should have mammograms less frequently -- every two years, rather than every year. Doctors should also stop teaching women to examine their breasts on a regular basis, according to the guidelines issued by an independent panel of experts in prevention and primary care appointed by the federal Department of Health and Human Services.